/Engine/Source/Runtime/Engine/Classes/Engine/FontFace.h
These should typically match the name of the package, but with a different extension.
virtual void CookAdditionalFilesOverride &40; const TCHAR &42; PackageFilename, const ITargetPlatform &42; TargetPlatform, TFunctionRef< void(const TCHAR &42;Filename, void &42;Data, int64Size)> WriteAdditionalFile &41;